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1.
Sci Total Environ ; 802: 149765, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34454141

RESUMEN

There is a growing global recognition that microalgae-based biofuel are environment-friendly and economically feasible options because they incur several advantages over traditional fossil fuels. Also, the microalgae can be manipulated for extraction of value-added compounds such as lipids (triacylglycerols), carbohydrates, polyunsaturated fatty acids, proteins, pigments, antioxidants, various antimicrobial compounds, etc. Recently, there is an increasing focus on the co-cultivation practices of microalgae with other microorganisms to enhance biomass and lipid productivity. In a co-cultivation strategy, microalgae grow symbiotically with other heterotrophic microbes such as bacteria, yeast, fungi, and other algae/microalgae. They exchange nutrients and metabolites; this helps to increase the productivity, therefore facilitating the commercialization of microalgal-based fuel. Co-cultivation also facilitates biomass harvesting and waste valorization, thereby help to build an algal biorefinery platform for bioenergy production along with multivariate high value bioproducts and simultaneous waste bioremediation. This article comprehensively reviews various microalgae cultivation practices utilizing co-culture approaches with other algae, fungi, bacteria, and yeast. The review mainly focuses on the impact of several binary culture strategies on biomass and lipid yield. The advantages and challenges associated with the procedure along with their respective cultivation modes have also been presented and discussed in detail.


Asunto(s)
Microalgas , Biodegradación Ambiental , Biocombustibles , Biomasa , Técnicas de Cocultivo
2.
J Environ Manage ; 292: 112746, 2021 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-34022651

RESUMEN

In the present study, a two-step bioaugmentation strategy (TSBS) was implemented by using indigenous bacterial consortium to enhance the degradation of total petroleum hydrocarbons (TPH) from petroleum refinery sludge (PRS). A bacterial consortium was developed using four indigenous isolated strains, Dietzia sp. IRB191, Dietzia sp. IRB192, Staphylococcus sp. BSM19 and Stenotrophomonas sp. IRB19 from PRS. The optimum conditions of pH, temperature, and sludge concentration were 7, 34 °C, and 2% (w/v), respectively, for maximum TPH degradation, obtained using one variable at a time approach. Under the optimal culture conditions, the developed consortium was inoculated twice to the culturing medium, at the beginning (0th day) and again on the 10th day for implementing a novel TSBS. The maximum TPH degradation of 91.5 ± 2.28% was found with TSBS, which was 1.18 times higher than that of SSBS (77.3 ± 2.6%) in 15 days of incubation. GC-FID study also confirmed that the TPH present in the PRS was effectively degraded by the bacterial consortium with TSBS. The TPH degradation by using TSBS proceeded according to the first-order kinetics with a rate constant of 0.155 d-1. Hence, biodegradation using a TSBS can be considered an effective and eco-friendly process for safe disposal of petroleum refinery sludge.


Asunto(s)
Petróleo , Contaminantes del Suelo , Bacterias/genética , Biodegradación Ambiental , Hidrocarburos , Microbiología del Suelo , Contaminantes del Suelo/análisis
3.
J Environ Manage ; 271: 111041, 2020 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-32778320

RESUMEN

Lipid production in microalgae under nitrogen (N) starved condition can be enhanced by excess phosphorus (P) supply in the second stage of two-stage cultivation strategy. However, implementing two-stage cultivation is difficult in large-scale cultivation system as it requires high energy of transferring large algal biomass from first stage to second stage. To address this problem, we have optimized a continuous two-stage (CTS) cultivation strategy using Chlorella sp. HS2, where nitrogen in the growth environment is depleted naturally via consumption. To enhance both biomass and lipid productivity this strategy explored supplementation of additional P from 50% to 2500% of the initial concentration at the start of N-limited second stage of growth. The results of the optimization study in photobioreactor (PBR) showed that supplementing 500% of initial P and 100% of initial other nutrients (O) (N0-P500-O100) on 5th day showed the maximum biomass productivity of 774.4 mg L-1 d-1. It was observed that Chlorella sp. HS2 grown in PBR yielded higher biomass (3.8 times), lipid (6.1 times) and carbohydrate (5.5 times) productivity in comparison to the open raceway ponds (ORP) study, under optimum nutrient and carbon supply condition. The maximum lipid (289.6 mg L-1 d-1) and carbohydrate (219.2 mg L-1 d-1) productivities were obtained in TPBR-3, which were 1.9 and 1.3 times higher than that of TPBR-2 (+ve control) and 9.6 and 3.7 times higher than that of TPBR-1 (-ve control), respectively. Fatty acid mainly composed of C16/C18 (84.5%-85.7%), which makes the microalgal oil suitable for biofuel production. This study concluded that feeding excess amount of P is an effective and scalable strategy to improve the biomass and lipid productivity of CTS cultivation.


Asunto(s)
Chlorella , Microalgas , Biocombustibles , Biomasa , Fósforo , Fotobiorreactores
4.
Environ Sci Pollut Res Int ; 26(26): 27396-27406, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31327138

RESUMEN

This study investigated the growth-dependent role of algal organic matters (AOMs) to achieve high removal efficiency (R.E) of microalgae. The results showed that the microalgae cells produced 96 ± 2% of total AOMs as loose bound AOMSS (LB-AOMs) and 4 ± 1% as cell-bound (CB-AOMs) in exponential phase. In stationary phase, LB-AOMs and CB-AOMs were 46 ± 0.7percentage and 54 ± 0.2 percentage, respectively. The R.Es in exponential and stationary phase were 83 ± 2.6% and 66 ± 1.2%, respectively. It is found that the difference of biomass concentration (between exponential and stationary phase) had no significant impact on the R.E (P > 0.01). Further investigations revealed that LB-AOMs inhibit flocculation in exponential and CB-AOMs in stationary phase; however, CB-AOMs showed stronger inhibition than the LB-AOMs (P < 0.01). The provision of calcium (17 ± 0.9 mg/L) to the culture reduced the AOMs inhibition and improved the R.E from 66 ± 1.2% (in control) to 90 ± 4.2%. An increase in R.E was attributed to the interaction of calcium with AOMs and subsequently acting as a flocculant. The findings of this study can be valuable to improve the performance of auto-flocculation technology, which is mainly limited by the presence of AOMs. Graphical Abstract.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Microalgas , Biomasa , Calcio , Floculación , Microalgas/crecimiento & desarrollo
5.
Sci Total Environ ; 682: 475-484, 2019 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-31128367

RESUMEN

Intensive use of chemical fertilizer results in environmental pollution that disturbs the local ecosystem and causes reduction in the long-term crop yield. There is a need to explore the alternative source of plant nutrition such as de-oiled microalgal biomass as biofertilizer for sustainable production of food crops in a relatively pollution free environment. This study reports sustainable and improved agriculture of rice crop (cv. IR 36) by valorizing de-oiled microalgal biomass waste (DOMBW) of Scenedesmus sp., as eco-friendly fertilizer. The microalga (MA) was cultivated in open raceway pond using wastewater and flue gas. Performance evaluation and comparison of DOMBW with respect to growth and yield of rice plants vis-à-vis commercial chemical fertilizers (CF) and vermicompost (VC) applied individually or together, established the superiority of the former. The experiment comprised of five nutrient management treatments (CF100, VC100, MA100, MA50+CF50, and MA50+VC50) meeting 100% nitrogen (N) recommendation either through a single source or combined application in the soil. Combining the application of microalgal based organic fertilizer with chemical fertilizer (MA50+CF50), showed the highest performance in terms of plant height, tiller number, biomass, and grain yield. At the harvest stage, MA50+CF50 also resulted in maximum plant dry weight, panicle weight, and 1000-grain weight in comparison to other treatments. This study revealed that the application of DOMBW as a biofertilizer is potentially sustainable and effective in improving the yields of rice crop with reduced use of chemical fertilizer.


Asunto(s)
Agricultura/métodos , Fertilizantes/análisis , Microalgas , Biomasa , Oryza/crecimiento & desarrollo , Eliminación de Residuos Líquidos/métodos
6.
Bioresour Technol ; 276: 110-118, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30616209

RESUMEN

In this work, the two-stage cultivation of Chlorella sp. HS2 for enhancing the lipid productivity was optimized by adjusting the duration of nitrogen-replete (N+) and -deplete (N-) stages within a 9 day period using urea as nitrogen source. The highest lipid content of 36.7% and productivity of 216.9 mg L-1 d-1 were obtained under five days of N+ followed by four days of N- conditions. Replenishing phosphorus and other nutrients (N-P+O+) at the beginning of the nutrient-starvation resulted in 1.55 and 1.68-folds improvement in lipid productivities compared to the single stage and zero nutrient controls (N-P-O-), respectively. The estimated biodiesel properties based on the fatty acid profiles met all criteria of international standards. The findings of this study indicate that properly adjusting the period of nitrogen availability as well as the presence of other nutrients is highly important in order to maximize the biofuel productivity in two-stage microalgal cultivation.


Asunto(s)
Chlorella/metabolismo , Lípidos/biosíntesis , Nitrógeno/metabolismo , Biocombustibles , Ácidos Grasos/biosíntesis , Microalgas/metabolismo , Fósforo/metabolismo
7.
Recent Pat Biotechnol ; 10(1): 30-42, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27585483

RESUMEN

BACKGROUND: In recent times, when energy crisis compounded by global warming and climate change is receiving worldwide attention, the emergence of algae, as a better feedstock for third-generation biofuels than energy crops or plants, holds great promise. As compared to conventional biofuels feedstocks, algae offer several advantages and can alone produce a significant amount of biofuels sustainably in a shorter period to fulfill the rising demand for energy. OBJECTIVE: Towards commercialisation, there have been numerous efforts put for- ward for the development of algae-derived biofuel. This article reviews and summarizes the recent inventions and the current trends that are reported and captured in relevant patents pertaining to the novel methods of algae biomass cultivation and processing for biofuels and value-added products. In addition, the recent advancement in techniques and technologies for microalgal biofuel production has been highlighted. METHODS: Various steps involved in the production of algal biofuels have been considered in this article. Moreover, the work that advances to improve the efficiency and cost-effectiveness of the processes for the manufacture of biofuels has been presented. Our survey was conducted in the patent databases: WIPO, Spacenet and USPTO. RESULTS: There are still some technological bottlenecks that could be overcome by designing advanced photobioreactor and raceway ponds, developing new and low cost technologies for biomass cultivation, harvesting, drying and extraction. CONCLUSION: Recent advancement in algae biofuels methods is directed toward developing efficient and integrated systems to produce biofuels by overcoming the current challenges. However, further research effort is required to scale-up and improve the efficiency of these methods in the upstream and downstream technologies to make the cost of biofuels competitive with petroleum fuels.


Asunto(s)
Biocombustibles/microbiología , Microalgas/crecimiento & desarrollo , Biomasa , Cambio Climático , Calentamiento Global , Invenciones , Patentes como Asunto
8.
J Gen Appl Microbiol ; 62(1): 7-13, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26923125

RESUMEN

The potential of an inorganic fertilizer as an alternative nutrient source for the cultivation of Scenedesmus sp. IMMTCC-6 was investigated. With a preliminary study at a shake-flask scale, the microalgae cultivation was scaled up in a photobioreactor containing an inorganic fertilizer medium. Microalgae cultured in a shake flask containing 0.1 g L(-1) of urea and 1.0 g L(-1) of NPK (Nitrogen: Phosphorus: Potassium) fertilizers showed a promising result in biomass productivity. During the scale-up study in a photobioreactor the specific growth rate (µ d(-1)), biomass yield (g L(-1)), and total biomass productivity (mg L(-1) d(-1)), was found to be 0.265, 1.19 and 66.1, respectively. The lipid yield (%) as per dry cell weight (DCW) and lipid productivity (mg L(-1) d(-1)) was found to be a maximum of 28.55 and 18.87, respectively, in a stationary phase of the microalgae growth. The fatty acids methyl ester profile was proven to be desirable for biodiesel production.


Asunto(s)
Medios de Cultivo/química , Fertilizantes , Metabolismo de los Lípidos , Scenedesmus/crecimiento & desarrollo , Biomasa , Lípidos/análisis , Nitrógeno/metabolismo , Fósforo/metabolismo , Fotobiorreactores/microbiología , Potasio/metabolismo , Urea/metabolismo
9.
J Microbiol Biotechnol ; 23(9): 1260-8, 2013 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-23727795

RESUMEN

A series of experiments were carried out with three native strains of microalgae to measure growth rates, biomass, and lipid productivities. Scenedesmus sp. IMMTCC-6 had better biomass growth rate and higher lipid production. The growth, lipid accumulation, and carbon dioxide (CO2) consumption rate of Scenedesmus sp. IMMTCC-6 were tested under different NaOH concentrations in modified BBM. The algal strain showed the maximum specific growth rate (0.474/day), biomass productivity (110.9 mg l(-1) d(-1)), and CO2 consumption rate (208.4 mg l(-1) d(-1)) with an NaOH concentration of 0.005 M on the 8(th) day of cultivation. These values were 2.03-, 6.89-, and 6.88-fold more than the algal cultures grown in control conditions (having no NaOH and CO2). The CO2 fixing efficiency of the microalga with other alternative carbon sources like Na2CO3 and NaHCO3 was also investigated and compared. The optimized experimental parameters at shake-flask scale were implemented for scaling up the process in a self-engineered photobioreactor. A significant increase in lipid accumulation (14.23% to 31.74%) by the algal strain from the logarithmic to stationary phases was obtained. The algal lipids were mainly composed of C16/C18 fatty acids, and are desirable for biodiesel production. The study suggests that microalga Scenedesmus sp. IMMTCC-6 is an efficient strain for biodiesel production and CO2 biofixation using stripping solution of NaOH in a cyclic process.


Asunto(s)
Dióxido de Carbono/metabolismo , Microalgas/metabolismo , Scenedesmus/crecimiento & desarrollo , Scenedesmus/metabolismo , Hidróxido de Sodio/metabolismo , Biocombustibles/análisis , Biomasa , Carbono/metabolismo , Ácidos Grasos/química , Ácidos Grasos/metabolismo , Microalgas/crecimiento & desarrollo , Fotobiorreactores/microbiología
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